Herpes simplex virus-1 (HSV-1) and herpes simplex virus-2 (HSV-2) are present as either lytic or latent herpes viruses, and are the causative agents in cold sores (HSV-1) and genital herpes, typically associated with lesions in the region of the eyes, mouth, and genitals (HSV-2) (Roizman, Spear). Both HSV-1 and HSV-2 viral infections are recurrent infections, often existing in a repressed condition which can be activated in the form of lesions by a variety of stimuli.
Herpes infection can be treated with acyclovir, an acyclic nucleoside. The drug usually works in primary viral infection to limit the severity of infection. However, viral infection often recurs after drug treatment is stopped, and resistance to the drug may limit its usefulness over an extended treatment period (Erlich, Mertz).